1. Field of the Invention
The present invention relates to Fibre Channel networks, and more particularly to a Fibre Channel switch element that can operate at a high speed.
2. Background of the Invention
Fibre Channel is a set of American National Standard Institute (ANSI) standards, which provide a serial transmission protocol for storage and network protocols such as HIPPI, SCSI, IP, ATM and others. Fibre Channel provides an input/output interface to meet the requirements of both Channel and network users.
Fibre Channel supports three different topologies: point-to-point, arbitrated loop and Fibre Channel fabric. The point-to-point topology attaches two devices directly. The arbitrated loop topology attaches devices in a loop. The Fibre Channel fabric topology attaches host systems directly to a fabric, which are then connected to multiple devices. The Fibre Channel fabric topology allows several media types to be interconnected.
In Fibre Channel, a path is established between two nodes where the path's primary task is to transport data from one point to another at high speed with low latency, performing only simple error detection in hardware.
Fibre Channel fabric devices include a node port or “N_Port” that manages fabric connections. The N_port establishes a connection to a fabric element (e.g., a switch) having a fabric port or “F_port”. Fabric elements include the intelligence to handle routing, error detection, recovery, and similar management functions.
A Fibre Channel switch is a multi-port device where each port manages a simple point-to-point connection between itself and its attached system. Each port can be attached to a server, peripheral, I/O subsystem, bridge, hub, router, or even another switch. A switch receives messages from one port and automatically routes it to another port. Multiple calls or data transfers happen concurrently through the multi-port Fibre Channel switch.
Fibre Channel switches use memory buffers to hold frames received and sent across a network. Associated with these buffers are credits, which are the number of frames that a buffer can hold per fabric port.
Current Fibre Channel standards define switch port/link operations to occur at 1 gigabit per second (“G”), 2 G, 4 G and 10 G. However, as bandwidth increases a need for 20 G, 40 G or higher port/link operation will occur. Conventional standards and Fibre Channel switches do not provide Fibre Channel switches that can operate at such high speeds.
Therefore, there is a need for a Fibre Channel switch whose ports can be selected to operate at high speeds, for example, at 10 G, 20 G or 40 G.